Thermoplastic compositions based on polyolefines and polyamides

ABSTRACT

THERMOPLASTIC COMPOSTITIONS CONSISTING OF POLYOLEFINES VERY FINELY DISPERSED IN POLYAMIDES ARE MADE BY DISPERSING THE OLEFINE IN A DIAMINE-DICARBOXYLIC ACID SALT SOLUTION, AND THEN SIMULTANEOUSLY POLYMERIZING THE OLEFINE AND POLYCONDENSING FOR DIAMINE ADN DICARBOXYLIC ACID BY HEATING UNDER PRESSURE.

United States Patent THERMOPLASTIC COMPOSITIONS BASED ON POLYOLEFINES AND POLYAMIDES Pierre Grosjean, Sainte-Foye-les-Lyon, and Alain Palsky,

Caluire, Rhone, France, assignors to Societe Rhodiaceta, Paris, France N0 Drawing. Filed Mar. 21, 1969, Ser. No. 809,384 Claims priority, application France, Mar. 22, 1968,

145,008 Int. Cl. C08g 41/04 U.S. Cl. 260-857 L 3 Claims ABSTRACT OF THE DISCLOSURE Thermoplastic compositions consisting of polyolefines very finely dispersed in polyamides are made by dispersing the olefine in a diamine-dicarboxylic acid salt solution, and then simultaneously polymerizing the olefine and polycondensing the diamine and dicarboxylic acid by heating under pressure.

The present invention relates to thermoplastic compositions based on polyolefines and polyamides produced from diacids and diamines.

Attempts have for a long time been made to obtain easily shaped thermoplastic compositions from polymers of diiferent properties which are incompatible in the fused state or in the solid state. In order that it should be possible to shape these compositions without difficulties in the molten state, and especially by extrusion, it is necessary Attempts have been made to obtain finer dispersions by using either a modified polyolefine containing acid groups which by virtue of their ionic action produce finer inclusions of diameter less than or equal to 5 microns, or by incorporating into the starting mixture a diseprsing agent such as a fatty acid or an N-substituted copolyarnide. However, the use of modified polymers or additional third substances generally adversely affect the physico-chemical characteristics of the resulting compositions compared with those of compositions prepared from the unmodified polyamide and polyolefine. Furthermore these processes necessitate an additional malaxating stage, which is frequently long and onerous, between the operations of preparing the polymer and of shaping the mixture.

It is also known to prepare mixtures of a polyamide and a polyolefine by adding a preformed polyolefine to the monomers from which the polyamide is made. By this process, rather irregular dispersions are obtained in which the diameter of the inclusions does not fall below microns.

The present invention provides compositions based on two incompatible polymers, obtained in a single operation. They contain 50 to 99% by weight of a polyamide produced from at least one diacid and at least one diprimary diamine and 50 to 1% by weight of a polyolefine, the said polyolefine being dispersed as a discontinuous phase in the form of particles of average diameter less Patented Feb. 29, 1972 than 5 microns, and preferably less than 3 microns, in the said polyamide as continuous phase.

Where the polyolefine constituent is present in the mixture in small amounts, the softening point and the behaviour in the molten state of the compositions of the invention are very close to those of the base polyamide, and the compositions can be easily shaped on devices, and in accordance with processes, usually employed for polyamides.

As the percentage of polyolefine in the composition increases, certain physico-chemical characteristics change, in particular the impact resistance, and the moisture uptake.

The polyamide constituent of the compositions according to the invention is preferably polyhexamethylene adipamide but it is also possible to use, for example, other polyadipamides or polysebacamides, polyazelamides, or polyterephthalamides.

The salts which form the polyamides and which can be used in the present invention are produced from essen tially equimolecular amounts of diacids of formula:

in which R is a divalent aliphatic, cycloaliphatic, aromatic or araliphatic optionally substituted hydrocarbon radical, and of di-primary diamines of formula:

in which R is a divalent aliphatic, cycloaliphatic or araliphatic optionally substituted hydrocarbon radical. In general the preferred polyamides are substantially linear, fibre-forming polyamides consisting essentially of units of the formula:

where R is polymethylene of 4 to 8 carbon atoms and R is polymethylene of 2 to 10 carbon atoms or p-phenylene, R and R together containing at least 8 carbon atoms.

The polyolefine constituent is generally a polymer of at least one OL-CthYlOIllC (aliphatic, linear or branched cycloaliphatic or araliphatic) hydrocarbon having more than 4 carbon atoms or of a diethylenic hydrocarbon possessing conjugated double bonds. Preferred such polyolefines are the substantially linear polymers or copolymers of an olefine of the formula:

where R is alkyl of 3 to 16 carbon atoms, phenyl, phenyl- (lower alkyl) or (lower alkyl)phenyl, and R and R are each hydrogen or lower alkyl, or R and R together make up a polymethylene chain of 3 to 8 carbon atoms, which is unsubstituted or substituted by lower alky, and/ or of a diolefine of the formula:

where R, R and R are each hydrogen or lower alkyl or R and R together make up a polymethylene chain of 1 to 8 carbon atoms. V p

The ethylenic monomers used must be capable of polymerising, in the presence of a catalyst if necessary, in'an aqueous medium at a temperature of between 20. and 320 C. and under a pressure of less than 50 kg./cm. By way of example there may be quoted the polymers and copolymers of styrene, of a-methylstyrene, of vinyltoluene, of cyclohexene, of cyclopentadiene, of 1,3-cyclooctfidiene, of l-hexadecene, of l-dodecene, of l-nonene, of l-hexene, of 2-methylbutadiene, or of l-phenyl-Z-butene.

The compositions of the invention are prepared by heating a dispersion of at least one olefinic monomer corresponding to the desired polyolefine in an aqueous solution of the salt or salts of at least one diacid with at least one atmospheric pressure over the course of about 90 minutes di-primary diamine, to from 180 C. to 320 C. under a while the temperature reaches 280 C. The polymer compressure of 10 to 50 kgJem. with removal of water to position is kept under these conditions for one hour. It efiect simultaneous polymerization and polycondensation. then has a sufficient viscosity in the molten state to be During the heating, the polymerization of the olefinic comextruded in the form of a thin rod which is cooled and pound and the polycondensation of the salt which forms cut into granules. the polyamide take place simultaneously. The process The polymer composition obtained has a viscosity in may be operated continuously or discontinuously. The the molten state of 1,460 Po and a softening point of concentration of the aqueous salt solution in which the 265 C. Microscopic examination of the composition ethylenic monomer is dispersed should be from 20 to 85% shows that the polyolefine phase is finely and regularly by weight. dispersed in the polyamide in the form of inclusions of In certain cases it is possible, in order to favour the average diameter about 4microns. polymerization of the ethylenic monomer, to add to the The absence of physico-chemical interaction between reaction mixture a catalyst such as a peroxide, azodiisothe base constituents of the mixture is demonstrated by butyronitrile, or a redox system, and to vary the temchecking, on the one hand, the amount of styrene susperature and pressure conditions or the duration of one of pended in the water distilled from the reaction mixture the phases of the operation, in particular where there is by extracting the styrene with ether, and, on the other danger of a part of the olefinic monomer being stripped hand, the amount of polystyrene present in the polymer off during the removal of th water. composition. These two amounts correspond to the total The new process makes it possible to prepare the com- Styrene employed, which would not be the Case if P Y- positions of the invention in a single operation, renders mers were formed. the malaxating of the constituents on which the mixture To measure the amount of polystyrene in the mixture, is based superfluous, and does not cause any physicothe polyamide phase is dissolved in formic acid, and the chemical interaction between the constituents, as can be polystyrene residue is isolated by dissolving in tetrahydroeasily verified by isolating these constituents, for example furan, filtering the solution, and reprecipitating the polyby dissolving one of them. styrene with water. The polystyrene is then washed with Fillers, pigments, dyestuifs or stabilizers are optionally Wa er, dried and weighed. Spectroscopic anaiysis of the added to the aqueous starting solution. polystyrene isolated by this process shows an infrared The following examples illustrate the invention. In spectrum which agrees with the spectrum of reference these examples, the viscosity in the molten state is measp y y ured according to Standard Specification ASTM D 1238 Comparative experiments 62 T, in which the condition K has been modified to 285 C. in place of 275 C. after 15 minutes fusion. The softening temperatures are measured on the Townsend and Crowther apparatus. The molecular weights of the polyolefines are determined viscometrically.

Polyamide-polystyrene mixtures are prepared according to known processes such as: (a) malaxating a preformed polyamide and a preformed polystyrene; or (b) incorporation of preformed polystyrene, of molecular weight comparable to that obtained in Example 1, in the EXAMPLE 1 solution of hexamethylene diammonium adipate, and polycondensation according to the conditions of Example 1. The following are introduced into a stainless steel auto- In case (a), microscopic examination shows a rather irclave which has beforehand been purged with a stream of regular distribution of the polyolefine inclusions, with nitrogen: their diameter varying from 15 to 25 microns. In case 5,240 g. of a 50% by weight aqueous solution of hexa- (b), the average diameter of the polyolefine inclusions is methylene diammonium adipate; between 10 and 20 microns.

4.5 g. of pure acetic acid as viscosity stabilizer for the polyamide; and 250 g. of freshly distilled styrene. EXAMPLES The pressure in the autoclave is slowly raised to 18 Additional experiments were carried out as in Example kg./cm. and the temperature to 220 C. This pressure 1 and the following tables show the various conditions is kept constant, while the water is removed from the used. In Examples l-6 styrene is used as the olefine monoreaction mixture by distillation during the course of about 5 mer, and in Examples 7 to 12, various other olefine monoone hour. The pressure is then progressively reduced to mers are used.

TABLE I Example 1 2 3 4 5 6 Hexamethylene diammonium adipate (g.)- 5, 2/10 5, 240 Pure acetic acid (g.) 4. 5 4. 5 S rene (g.) 252 252 Methyl ethyl ketone peroxide (g.)

Duration of the cycle at 220 C. under 18 kg./ern. B (hours) Melt viscosity (polses) Softening point C.) Diameter of the polystyrene c 3 5 4 Molecular weight of the polystyrene 85, 000 100, 000 80, 000 110, 000

See footnotes at end of Table II.

TABLE II Example 7 8 9 10 ll 12 Hexamethylene diammoniurn adipate a (g.) 4,192 4,192 5,240 4,200 4,200 4,200 Pure acetic acid (g.) 3.6 3.6 4.5 4.5 3.6 3.6. Ethylene monomers (g.) l-dodecene (78), Cyclohexene l-hexadecene Cyclooetadrene Cyclopenta- Cyclopenstyrene (16). (66.5), (79), styrene (98), styrene diene (62), tadiene styrene (31) styrene (28.5). (32.6).

Methyl ethyl ketone peroxide Duration of the cycle at 220 (hours). Softening point C.) 265"-.- Melt viscosity (poises) 1,575..- Diameter of the polystyrene inclusions (mierons)... 3-4 3 I 50% strength by weight aqueous solution. b Polymerisation catalyst for the ethylenic compound. it Before distillation.

We claim:

1. Process for the preparation of a thermoplastic composition comprising 50 to 99% by weight of a substantially linear, fibre-forming polyamide consisting essentially of units of the formula:

where R is polymethylene of 4 to 8 carbon atoms and R is polymethylene of 2 to carbon atoms or p-phenylene, R and R together containing at least 8 carbon atoms and 50 to 1% by weight of a substantially linear polymer or copolymer of an olefine of the formula:

where R is alkyl of 3 to 16 carbon atoms, phenyl, phenyl (lower alkyl) or (lower a1kyl)pheny1, and R and R are each hydrogen or lower alkyl, or R and R together make up a polymethylene chain of 3 to 8 carbon atoms, which is unsubstituted or substituted by lower alkyl, and/or of a diolefine of the formula:

where R, R and R are each hydrogen or lower alkyl or R and R together make up a polymethylene chain of 1 to 8 carbon atoms, the said polyolefine being dispersed as a discontinuous phase in the form of particles less than 5 microns in diameter in the said polyamide as continuous phase which comprises heating a dispersion of at least one said olefine and/or diolefine in an aqueous solution of the salt or salts of at least one diacid of the 6 formula HOCOR -COOH with at least one di-primary diamine of the formula H N--R -NH to from 180 C. to 320 C. under a pressure of 10 to l g./cm. with removal of water to effect simultaneous polymerisation and polycondensation.

2. Process according to claim 1 in which the concentration of the said salt or salts in the said aqueous solution is from 20% to by weight.

3. Process according to claim 1 in which the said solution also contains a catalyst to promote the polymerization of the said olefine and/or diolefine.

References Cited UNITED STATES PATENTS 2,249,686 7/ 1941 Dykstra 260857 2,550,650 4/1951 Arnold 260857 2,820,770 1/1958 Adams 260857 3,243,478 3/1966 Seeling 260857 3,330,889 7/1967 Fukushima 260857 3,359,344 12/1967 Fukushima 260857 3,496,985 2/ 1970 Werner 260857 3,499,884 3/1970 Wood 26094.9

FOREIGN PATENTS 740,501 8/ 1966 Canada 260857 6,618,085 6/1967 Netherlands 260857 PAUL LIEBERMAN, Primary Examiner US. Cl. X.R.

26078 R, 857 D, 857 UN 

